The father of a 15-year-old autistic boy found dead in a Mississauga hotel room is struggling to make sense of the tragedy.

Boon Khor, 51, walked out of the courthouse in tears, trying to cope with the loss of his son Tony -- and the arrest of his wife.

Outside a Brampton courthouse, Khor told reporters there was some difficulty in the marriage. He and his wife Seow Cheng Sim, 51, had an argument Saturday morning, and she had mentioned getting a divorce.

"That's the first time she ever brought up the word, that she wanted a divorce," Khor said. "At that time I said, I will never bring up that word -- divorce. Why would you want to bring it up? If you want to divorce, go ahead. I never saw the signs coming, is what she was telling me. She said if you divorce me I will kill myself. I should have known."

Sim and the boy left shortly after.

Sim checked into a hotel room at the Homewood Suites Hotel on Edwards Boulevard, near Hurontario Street and Derry Road, on Saturday. According to Peel Police, Tony Khor was found dead Sunday just after 11 a.m. Officers say the boy died sometime after the two checked in.

Police called Boon on Sunday to tell him the grim news.

Tony was severely autistic and had trouble communicating. The family's neighbours are shocked with the news. One neighbour told CTV Toronto that Sim appeared to be a happy woman and often played outside with her son.

"I could see she loved him", said Sunil Kaboor. "She really took good care of him."

Tony was in a special class at St. Marcellinus Secondary School in Mississauga. Students remember a gentle boy who loved music and always had headphones on.

CTV Toronto's John Musselman reported that Boon still doesn't believe his wife killed their son. He thinks the death was an accident.

Sim was formally charged with first-degree murder Monday morning during an appearance in a Brampton courtroom. She remains in custody and will make another court appearance Friday.

With a report from CTV Toronto's John Musselman